ISSN:
1574-6968
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Two variants have been isolated from the wild-type Azospirillum lipoferum strain 4B. The first variant, 4VI, spontaneously emerged from the wild-type at frequencies in the order of 10−4 to 10−3 per cell generation. Compared to the wild-type, the 4VI variant gained (production of a carotenoid-like pigment, assimilation of certain carbohydrates) and lost (swimming motility, reduction of triphenyl tetrazolium chloride, acid production from certain sugars) apparently unrelated phenotypic characteristics. Only from the 4VI variant, a second atypical stable form, variant 4VII, which acquired laccase activity and ability to produce melanin, appeared under very specific conditions, namely growth at extremely low oxygen concentrations. Neither of the variants was able to revert to the parental phenotype. The results suggest that atypical non-motile laccase-positive isolates of A. lipoferum that are found in the rice rhizosphere originate from wild-type (motile, laccase-negative) cells via a two-step phenotypic switching event, a non-motile laccase-negative variant being an intermediate phase.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1574-6968.1999.tb13592.x
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